How does Tc-99m function as a SPECT imaging agent?

• A. It emits X-rays detectable by film
• B. It emits beta particles for therapeutic use
• C. It emits gamma rays detected to form 3D images
• D. It requires an MRI for imaging interpretation

Answer: (C)

Technetium-99m (Tc-99m) is widely used in SPECT (Single Photon Emission Computed Tomography) imaging primarily because it emits gamma rays. When Tc-99m is introduced into the body, it accumulates in specific tissues or organs based on the radiopharmaceutical's design and purpose. As it undergoes radioactive decay, it emits these gamma rays, which are then detected by the SPECT imaging system.

The gamma rays emitted are crucial because they can pass through body tissues and be detected externally, allowing the creation of three-dimensional images of the internal structures and functions of various organs. This capability to detect gamma emissions enables clinicians to visualize biological processes in real time, making Tc-99m a valuable tool in diagnostic imaging.

In contrast, the other options do not accurately describe the role of Tc-99m in SPECT imaging. Tc-99m does not emit X-rays, nor is it primarily used for therapeutic purposes through beta particle emission. Additionally, it does not require MRI for imaging interpretation; SPECT techniques utilize gamma detection independently. Thus, the function of Tc-99m as a gamma-emitting agent is what makes it suitable for SPECT imaging and central to its application in radioph